Preview:
Citation preview
Q-tron Audio Manual PA34B3R1 Page 1
Q-tron Audio
PERFORMANCE
DATA:......................................................................................8
CONTACT
INFORMATION...................................................................................9
Q-tron Audio
Q-tron Audio Manual PA34B3R1 Page 3
Q-tron Audio Introduction Thank you for choosing the PA34 OTL
amplifier from Q-tron Audio. The PA34 is a new improved OTL
amplifier with 10 time’s lower distortion than other OTL amplifiers
of similar output power.
Content of delivery
Box 1
1. Amplifier PA 34 2. Tubes 6C33C 4 pcs 3. Tubes 6N2n-EB 3 pcs 4.
Tubes 6N6P-I 2 pcs 5. monitor interface unit 6. adjustment
screwdriver
Box 2
1. Amplifier PA 34 2. Tubes 6C33C 4 pcs 3. Tubes 6N2n-EB 3 pcs 4.
Tubes 6N6P-I 2 pcs
Unpacking Box Put each wooden box on a table or other steady
surface. Make sure that the boxes is oriented correctly, i.e. that
the side marked top is facing upwards. Open the boxes by prying
open the metal flaps that is holding the top lid using a screw
driver. When all metal flaps are bent so they point upwards the lid
can be opened.
Remove packing material so that the amplifier can be lifted out of
the box, be aware of the weight and handle the amplifier
carefully.
Put the amplifier on a steady surface with the front panel facing
towards you.
Unpack all tubes cartons, the adjustment screwdriver and the
monitor interface unit and put them aside. Unpack all tubes one by
one and put them into the correct tube sockets as indicated by the
figure. NOTE! Output tubes are matched as a set of 4 and also to
each individual amplifier, make sure that the tubes are set in
their correct position in each amplifier.
Q-tron Audio Manual PA34B3R1 Page 4
Q-tron Audio
Tube placement
Note! V1, V3 and V4 are 6N2-EB, V2 and V5 are 6N6P, V6 – V9 are
6C33C-B
Controls and connectors Front panel
On switch with integrated on indicator, this is a switch button
which when pushed in will start the switch on sequence of the
amplifier. If function is normal the area around the switch button
will light up with green color after approximately 90 seconds. If
function is abnormal, i.e. if output offset voltage is too high the
amplifier will not switch on and the indicator will not be
lit.
Back panel
Input connector balanced
Q-tron Audio This connector accept a standard XLR male plug
Balanced/unbalanced switch
The switch should be set in the up position for balanced input and
down for unbalanced operation
Speaker connectors
These connectors accept 4mm banana type plugs, bare wire and spade
type connectors.
Mains power inlet with integrated fuse holder and mains
switch.
The power inlet accepts a standard power cord with IEC320 plug. The
2 mains fuses can be accessed if the power cord is removed and the
fuse cover/holder is removed, replace the fuses only with fuses of
same rating, (for 230VAC mains power fuse rating is 4A slow blow
and for 120VAC mains power fuse rating is 6.3A slow blow). The
mains switch power up the amplifier if it is set to position 1, in
position 0 the amplifier is disconnected from mains power.
Setup Connect the amplifier to the mains voltage with a standard
IEC 320 mains cable Connect speakers to the isolated binding posts
Connect a preamplifier to the connector marked input
Function
The amplifier is equipped with phono and XLR connectors for input
signal and isolated binding posts for connecting speakers. The
amplifier is equipped with an output offset voltage protection
circuit which protect any connected speakers in the case the
amplifier would give a too high DC voltage on the output. A fail
safe soft turn on circuit is also included.
Start up procedure Check that the front push button switch is not
pushed in. Switch on the mains switch on the back panel to position
1. Push in the front panel bush button, after approximately 1.5
seconds a “click” can be heard, this is an indication that the soft
turn on circuit is activated. After approximately 90 seconds the
area around the front panel push button will be lit green and the
amplifier is ready for operation.
If the offset voltage protection circuit is activated this is
indicated by the green area around the front panel bush button is
not lit. To de-activate the offset voltage protection the amplifier
has to be completely shutoff for at least 1 minute by setting the
mains switch on the back panel to position 0. After the 1 minute
delay the normal start up procedure can be followed.
Q-tron Audio Manual PA34B3R1 Page 6
Q-tron Audio NOTE! The amplifier must be connected to speakers or
other load in order to operate correctly, if not the offset voltage
protection circuit will switch off the amplifier automatically
directly after the start up sequence has been completed.
Bias and offset voltage check
We recommend to check offset and bias every 6 months, there is no
need for more frequent checks.
Controls and connector for bias and offset voltage check on the
rear panel
Bias control adjustment
Through these 2 holes the bias for each output tube pair can be
adjusted using the adjustment screw driver.
Monitor
This connector is used to connect the monitor interface unit when
adjusting the output tube bias point and offset voltage
Monitor interface unit
This unit is used when adjusting output bias and output offset
voltage. The unit connects with a cable to the monitor connector on
the rear of the amplifier.
NOTE! The monitor interface unit should only be connected to the
amplifier during testing and adjustment; it should be removed
during normal use.
The adjustment knob has 4 positions to select different test
points.
1. Bias current 2. Output offset volt 3. No function
The 2 test points are for connecting an auto ranging DVM
Note! The monitor interface unit is used for PA3, PA12 2-channel
amplifiers and the PA34 Monoblock, for use with PA34 the toggle
switch should be set to right position when the switch is facing
towards you.
Q-tron Audio Manual PA34B3R1 Page 7
Q-tron Audio Test procedure:
2. Connect an auto-ranging DVM to the monitor interface unit
3. Place the monitor interface unit so that the toggle switch faces
towards you
4. Switch on the amplifier and wait at least 30 minutes.
5. Turn the adjustment knob on the monitor interface unit to
position 1
6. Set the toggle switch to right position
7. Check the reading of the DVM for bias current, it should read
between 150 -250mV which is equivalent to a bias current of 300 –
500mA.
8. Turn adjusting knob to position 2
9. Check the reading of the DVM for offset voltage, it should be
less than 100mV note! the offset voltage can be positive or
negative but should in any case beless than 100mV
10. If readings are within specification you don’t need to do
anything, otherwise follow procedure described below.
Adjustment procedure for bias and offset
NOTE! The adjustment is sensitive so adjustments should be made by
turning the adjustment screwdriver a tiny amount each time, don't
turn more then 5 degrees each time!
To increase bias both potentiometers should be turned counter
clockwise. To decrease bias both potentiometers should be turned
clockwise. For every adjustment of the potentiometers bias and
offset should be measured. Adjust bias step by step until it reads
between 150 - 250mV on the DVM To increase or decrease offset the
potentiometer marked V8, should be adjusted. For every adjustment
offset should be measured, adjust offset so it is between -100mV
and +100mV
Q-tron Audio Manual PA34B3R1 Page 8
Q-tron Audio Performance data:
Output power in 8 ohm load 80W at 1% distortion at 1kHz Output
power in 4 ohm load 60W at 1% distortion at 1kHz
Output impedance <0.4ohm
Harmonic Distortion 0.01% at 1kHz and 2W output power 0.1% at 1kHz
and 25W output power
Power bandwidth 10 – 150000 Hz -3dB
Noise and hum 90 dB below 80W output power, (10 – 200000Hz) 100 dB
below 80W output power, A-weighting filter
Line voltage 230V or 120V ± 10% Power consumption 600W
maximum
Dimensions chassis 275 x 370 x 225 mm, (W x D x H) Dimensions
overall 275 x 370 x 335 mm, (W x D x H)
Tube complement 9 tubes in total, (6C33C x 4, 6N6P-I x 2, 6H2n-EB x
3
Input connectors:
Output connectors CE approved isolated binding posts accepting 4mm
banana connectors, spades and bare wire
Line voltage connectors IEC320 jack with integrated mains switch
and dual fuses
Weight 18kg
www.qtron.se sales@qtron.se